After spending a little time with some jewelry makers recently, it’s clear that artistic talent is a must for this vocation. Although technology has improved over the years, jewelry making borrows techniques from ancient days.

While jewelry can be (and is) made from a variety of metals, gold continues to be the primary choice today as it was in Egypt as far back as 3000 B.C. As then, this is because gold is rare, doesn’t tarnish and is malleable. That means that gold can be worked fairly easily. The word jewellery – jewelry in American English – is derived from the word jewel. This is the anglicized version from the Old French “joule.” Original word origins appear to be the Latin word “jocale,” meaning plaything.

The techniques for creating jewelry can sound more like a day at the steel mill – forging, casting, soldering, welding, rolling, trimming and carving. The photo on this page shows the casting technique of a jewelry maker who was casting a ring and five feather pins from yellow gold. The second photo shows the cast product still attached to the button (ingot).

The gold raw material is either purchased from refineries or from individuals interested in cashing out some unused jewelry. As with many metal processes and unlike some, jewelry material is infinitely recyclable. The purity of 14K gold is 58.5%, and 18K is 75% pure. Yellow gold is alloyed with some amounts of copper, zinc, nickel and silver. White gold is currently seeing an increase in popularity. It is alloyed with nickel and silver and tends to be a little harder than yellow gold thanks to the higher nickel content.

The process of creating a mass-produced piece of jewelry begins with the creation of a design. The design is then carved into wax exactly as the final piece will look. The wax part is cast into plaster material to make a mold of the part. The plaster mold is “baked out” in a high-temperature oven at 1200-1400˚F to volatilize the wax. For good reason, this has long been known as the “lost-wax” process. Toward the end of this process, the metal – 14K yellow gold, in this case – is melted in a separate carbon crucible. The melting point for 14K gold is about 1650˚F, and it will be poured at 1750-1800˚F. The carbon is self-fluxing, resulting in the purest final product possible.

When the gold is fully melted, the plaster mold is removed from the oven and placed over a vacuum source. The gold is poured into the mold, and the vacuum draws it into the finely sculpted mold detail remaining from the lost wax. The plaster mold is removed, and the metal piece is appropriately prepared. It is then used to create another mold in a silicon-rubber product. This mold will be used to create as many wax pieces as are needed for the production run, which will be used for additional castings as described earlier.

The casting photo shows that one ring was cast along with five quill-feather pins. For each quill, a wax part was made. Several of these were put together in the plaster mold to optimize the pour. Note the as-cast detail visible in the feather. The gold button at the bottom, which was the top of the mold, will simply be recycled into another cast.

Now that the cast is complete, the individual pieces will be cut from the “ingot.” Due to the fine detail of the cast material, very little work needs to be done to clean up the casting. Usually, just a buff or a light tumble is sufficient to remove the casting remnants. For pieces like the ring, gemstones will be added by first grinding a seat into the metal, inserting the stone and roll forming the gold to lock the gem into place.

Now you know what it takes to produce the beautifully detailed jewelry that you may plan to get that special someone this holiday season. Christmas will be here before you know it. Stop at your favorite jeweler soon. IH


Red PresentThis article is featured in Industrial Heating's Top-10 Heat-Treated Holiday Gifts.  Click on the present to find more gift ideas and to learn how these gifts benefit from thermal processing.